Sharing a predator: can an invasive alien pest affect the predation on a local pest?

Anaïs Bompard (1) , Coline C Jaworski (2) , Nicolas Desneux (3) , Philippe Bearez (3)

1 iEES - Institut d'écologie et des sciences de l'environnement de Paris
2 EDB - Evolution et Diversité Biologique
3 ISA - Institut Sophia Agrobiotech

Invasive species can strongly affect biotic interactions in ecosystems, interacting both directly and indirectly with local species. In European tomato greenhouses , the invasive alien pest Tuta absoluta may impact the population dynamics of other pests like whiteflies. Besides inducing damages to the host plant and competing for resources with local pests, this alien species may exert a predator-mediated interaction on local pests sharing common natural enemies. Biocontrol agents usually used against whiteflies may also prey upon T. absoluta and this could alter the dynamics of local pest populations. We evaluated possible resource competition and predator-mediated interactions in a system involving one mirid predator Macrolophus pygmaeus and two pests, T. absoluta and a local whitefly, Bemisia tabaci, on greenhouse tomatoes. Results showed that both resource competition and predator-mediated interactions occurred simultaneously. In the presence of the shared predator, there was a short-term positive effect of T. absoluta on B. tabaci [up to 5.9-fold increase of B. tabaci juveniles (egg ? larvae) after four weeks]. However, in the long-term there was a negative predator-mediated interaction of T. absoluta on B. tabaci, i.e., after ten weeks the density of B. tabaci was 7.3-fold lower in the presence of the invasive pest. We emphasize the critical role of generalist predators in managing both local and invasive alien pest populations and that the strength and direction of predator-mediated indirect interactions can depend on the time scale considered.

Mots clés: Tuta absoluta; Resource competition; Apparent competition; Apparent mutualism; Bemisia tabaci; Macrolophus pygmaeus

Domaines: Sciences du Vivant [q-bio]; Ecologie, Environnement; Interactions entre organismes

Anaïs Bompard, Coline C Jaworski, Nicolas Desneux, Philippe Bearez. Sharing a predator: can an invasive alien pest affect the predation on a local pest?. Population Ecology, 2013, 55 (3), pp.433-440. ⟨10.1007/s10144-013-0371-8⟩. ⟨hal-02107771⟩